1. Field of the Invention
The present invention relates to testing of saliva samples for drugs of abuse, more particularly, to a device and process which permits the saliva sample to be treated and incubated for a predetermined period of time prior to being introduced to an immunoassay test strip.
2. Description of Related Art
The increased availability and use of drugs of abuse by the general population has caused employers, governmental agencies, sports groups and other organizations to utilize drug screening both as a condition of employment and in order to maintain safety in the work place. Screening tests for the detection of drugs of abuse range in complexity from simple immunoassay tests to very complex analytical procedures. Over the years the speed and specificity of immunoassays have made them one of the most accepted methods for screening for drugs of abuse in body fluids. Typical drug screening tests are performed for the purpose of quickly identifying on a qualitative basis the presence of drugs in a body fluid which may be urine or saliva. A complete analysis of the sample may then be carried out in a laboratory only if the preliminary screening results are positive. More and more such drug screenings are taking place on site or at the work place and are generally carried out by testing personnel who are generally not technically trained, such as laboratory technicians. It is thus important that the drug screening procedure is simple but yet reliable. Further, the test apparatus must be such so as to enable the testing personnel to avoid all contact with the fluid specimen which is being tested.
While blood and urine samples have long been the primary fluids used for testing for disease as well as for evidence of substance abuse, there is increasing interest in testing of saliva specimens. Some advantages in testing saliva are that it is relatively easy to obtain a saliva sample and that a saliva sample cannot be adulterated. Also, testing of saliva gives a result in real time within a span of several hours as compared to urine which gives a test result after-the-fact.
However, the collection and analysis of saliva for diagnostic purposes is complicated by the relatively high viscosity of the fluid. Thus, once a saliva test sample is introduced into a test device, there is little user control over the subsequent events since the fluid flow determines the speed and timing of all of the reactions. Also, if the sample requires pre-treatment with specific reagents to dilute or denature interferants, modify analyte structure, or release analyte from binders, such treatments are generally performed outside the confines of the test device. It has become apparent that numerous advantages would be derived from a self-contained saliva sample test device that allows control over the test sample and is simple to use so that more accurate test results may be obtained.
U.S. Pat. No. 6,634,243—Wickstead is such a prior art device which has an inadequate and ineffective provision for control of the test sample. Other relevant prior art includes U.S. Pat. No. 6,267,722—Anderson et al, U.S. Pat. No. 6,214,629—Freitag et al and U.S. Pat. No. 5,630,986—Charlton et al.
U.S. Pat. No. 6,576,193—Cui et al is a prior art device which has a fluid metering valve to control the volume of test fluid released to the test strip, but is not concerned with testing of saliva samples nor with control of speed or timing of reactions involving a saliva test sample.